Experimental study on particle feeding and mixing in the bottom zone of a circulating fluidized bed

Abstract

The mixing behaviors of the feeding particles in the bottom zone of a circulating fluidized bed with a rectangular cross-section of 0.3 m×0.2 m and a height of 2 m were investigated by monitoring transient pressure drop and thermal tracing method. The effects of the feeding particle size, feeding port location (relative to dense bed surface), feeding gas velocity and fluidization gas velocity were examined. The bed collapse technique was also used to examine the lateral distribution of the feeding particles for four typical cases to give reference results. Results show that the mixing behaviors are greatly dependent on particle size. Under the condition that the feeding port is fully submerged in the dense bed, a hot spot occurs as the feeding gas velocity is no more than 0.24m/s. Increase in feeding gas velocity and fluidization gas velocity can both promote the mixing of the feeding particles with bed material.